What are the limits to texture/resources pack resolutions?

Why are most packs 512 x 512 at most? why do 1024 x 1024 or larger packs freeze minecraft minecraft when applying but run fine while playing? Invisible packs probably aren't support but if they were would everything just look like they were replaced with barrier blocks? what if invisible player skins were supported how would they differ from invisibility effect without particles? do resolutions need to be even numbers why not odd or decimal? what would a 15.1457 x 15.1457 texture pack look like? can resources pack models be so small they disappear or so big they cover the world perhaps via mods? would 0.00009 x 0.00009 pack look the same as 1 x 1? what about 1/0 or 45 x 65 packs? you get the idea u/AntVenom